On June 22, 1969, an oil slick and debris in the Cuyahoga River caught fire in Cleveland, Ohio, drawing national﻿ attention to environmental problems in Ohio and elsewhere in the United States.

It is unclear what caused the fire, but most people believe sparks from a passing train ignited an oil slick in the Cuyahoga River. This was not the first time that the river had caught on fire. Fires occurred on the Cuyahoga River in 1868, 1883, 1887, 1912, 1922, 1936, 1941, 1948, and in 1952.